configurer X-server

Pour récupérer le fichier xorg.conf sur les systèmes qui n'en ont pas. Quand X est lancé et tourne correctement, je fais un

#X :1 -configure qui me donne en retour un xorg.conf.new que je peux ensuite customiser.

Pour lister et ajouter des modes j'utilise xrandr

et pour définir des modelines j'utilise : cvt

Je peux coller ensuite les modelines voulus dans le xorg.conf

(ce qui est utile quand la détection dcc du moniteur se fait mal)

Pour les intel915 qu'on trouve sur les P4 j'utilise aussi 915resolution pour patcher à la volée le bios.

Pour généner des modelines il y a aussi : videogen (mais jamais utilisé)

Il y a aussi un script que l'on trouve parfois installé : displayconfig-gtk

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II. Use xrandr to enable/disable/move/resize multiple outputs

II.1. Basics

Once the configuration file (xorg.conf) is updated, starting the server should enable some outputs by default. Their top-left corners will be at the same part of the image, but their modes will probably be different.

All outputs may be configured through xrandr (or the grandr graphic tool). To see the available outputs, just run xrandr:

  $ xrandr

  Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 2048 x 1152

  VGA-0 disconnected (normal left inverted right x axis y axis)

  DVI-0 disconnected (normal left inverted right x axis y axis)

  LVDS connected 1400x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm

   1400x1050 60.2*+

   1280x800 60.0

   1280x768 60.0

   1024x768 60.0 75.0

   800x600 60.3

   640x480 59.9

  S-video disconnected (normal left inverted right x axis y axis)

It shows that this board supports 4 outputs, names VGA-0, DVI-0, LVDS (the internal panel) and S-video (the TV output). Only LVDS is connected and it supports 6 modes at 60 Hz, and one at 75.

The mode marked with a star is the current mode.

The one marked with a plus is the preferred one. Most monitor report a preferred mode to the driver. And the server/driver will generally choose it by default.

II.2. Outputs naming convention

There are no standard naming convention as of today, it just depends on the driver, but it could change in the future.

At least the RadeonHD driver will print out a list of outputs as part of the /var/log/Xorg.0.log file generated by trying to start X. An example of output from the RadeonHD driver is

(II) RADEONHD(0): Output DVI-I_1/digital connected

(II) RADEONHD(0): Output DVI-I_1/analog disconnected

(II) RADEONHD(0): Output TV_7PIN_DIN disconnected

(II) RADEONHD(0): Output DVI-I_2/digital connected

(II) RADEONHD(0): Output DVI-I_2/analog disconnected

Where for example "DVI-I_1/digital" is the name of the digital output of the first DVI port.

For the internal laptop panel, external VGA, external DVI and TV, the drivers currently use:

the Intel driver uses LVDS, VGA, TMDS-1 (TMDS-2, ...), TV

the ATI driver uses LVDS, VGA-0 (VGA-1, ...), DVI-0 (DVI-1, ...), S-video

the RadeonHD driver uses PANEL, VGA_1 (VGA_2, ...), DVI-I_1/digital or DVI-I_1/analog (DVI-I_2/digital or DVI-I_1/analog, ...), TV_7PIN_DIN

the NV driver uses LVDS, VGA0 (VGA1, ...), DVI0 (DVI1, ...), ???

the MGA driver uses ???, VGA (or VGA1, VGA2, ...), DVI (or DVI1, DVI2, ...), ???

the Nouveau driver uses ???, Analog-0 (Analog-1, ...), Digital-0 (Digital-1, ...), ???

When manipulating VGA-0 output properties as below, you should use:

  $ xrandr --output VGA-0 <options>

II.3. Adding/removing heads dynamically

The old days where you had to restart X when plugging a new monitor are gone. With RandR 1.2, you can plug/unplug monitors whenever you want. Running the following line will query all outputs and enable them with their default mode:

  $ xrandr --auto

You may also disable one output using:

  $ xrandr --output LVDS --off

This may be useful for some buggy application that don't support multiple outputs well. Also, due to CRTC limitations (see the Caveats section below), it is often required to disable one output before enabling another since most hardware only support 2 at the same time.

II.4. Changing the mode

With the above xrandr output, you may change the LVDS mode to 1024x768 using:

  $ xrandr --output LVDS --mode 1024x768

The refresh rate may also be changed, either at the same time or independently:

  $ xrandr --output LVDS --mode 1024x768 --rate 75

II.5. Placing outputs in a virtual screen

Randr 1.2 provides the ability to create a large virtual screen and place multiple output in it, either with or without overlapping zones. To reduce memory consumption, drivers will often create a default virtual screen with small dimensions, for instance 1600x1200. Look at the output of xrandr to know your virtual screen dimensions. It would be 2048x1152 if xrandr reports:

  $ xrandr

  Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 2048 x 1152

If you plan to use multiple outputs displaying different zones, you should configure your xorg.conf by adding a Virtual line to subsection Display in the Screen section.

  Section "Screen"

   ...

   SubSection "Display"

   Depth 24

   Virtual 3000 2000

   EndSubSection

  EndSection

Then you place outputs using xrandr and the --right-of/--left-of/--above/--below options. For instance, to place your VGA output virtually-right of your internal panel, run:

  $ xrandr --output VGA --right-of LVDS

Note that hardware and memory limitations may severely restrict the size of your virtual screen, see the Caveats section below.

II.6. Adding new modes

Under some circumstances, some modes might be missing. For instance, if the monitor does not report correct EDID information. Or if the output didn't have a CRTC available at startup because another output was using it and you disabled it in th meantime.

If a mode exist, you may add it to one output with:

  $ xrandr --addmode S-video 800x600

If the mode does not exist, you may first create it by passing a modeline:

  $ xrandr --newmode <ModeLine>

You may create a modeline using the gtf or cvt utility.

III. xorg.conf based configuration

Running xrandr is convenient for dynamic configuration, but it may be annoying if you have to run it after every startup of your X server. Section III.6 summarizes all this by showing an example of modern configuration.

III.1. Per Output Config

Before configuring an output, you need to know how to specify it in the config file. To do so, you may add a Monitor-FOO option to the Device section to identify the monitor section for output FOO. For instance:

  Section "Device"

   Identifier "My Graphic Board"

   ...

   Option "Monitor-LVDS" "Internal Panel"

   Option "Monitor-VGA" "External VGA Monitor"

  EndSection

  Section "Monitor"

   Identifier "Internal Panel"

   ...

  EndSection

  Section "Monitor"

   Identifier "External VGA Monitor"

   ...

  EndSection

Then, all output-specific options should go in the corresponding Monitor section.

III.2. Placing outputs

Add the following line to place one monitor on the right of another one as xrandr --output FOO --right-of BAR would do:

  Section "Monitor"

   Identifier "FOO"

  EndSection

  Section "Monitor"

   Identifier "BAR"

   Option "RightOf" "FOO"

  EndSection

III.3. Changing DPI and DisplaySize

If your monitor size isn't detected correctly and thus generates a wrong DPI, you need to add a DisplaySize option to the corresponding monitor section. For output FOO, use:

  Section "Monitor"

   Identifier "MyMonitor"

   DisplaySize 304 228

  EndSection

  Section "Device"

   ...

   Option "Monitor-FOO" "MyMonitor"

  EndSection

III.4. Forcing outputs off or on

If for some reason one output of your graphic board is enabled while it should not, you might want to disable it (for instance because the number of CRTCs available is limited). To do so, add:

   Option "Ignore" "true"

If for some reason one output is disabled by the driver (for instance VGA-0 on Radeon Xpress 200 because load detection is not reliable in the driver yet), you might want to enable it by force. To do so, add:

   Option "Enable" "true"

Then, you might need to add modes since such an output may not query modes correctly. See "Forcing a preferred mode" to do so.

III.5. Forcing a preferred mode

This is one of rare cases where the ModeLine open is still useful these days. If the preferred mode reported by your monitor isn't the one you want by default, or if there is no preferred mode and the driver does not choose the right one, you might want to force another mode on an output.

Assuming you want to force 1280x1024 at 75Hz at startup, add something like the following to the Monitor section:

   Modeline "1280x1024_75.00" 138.54 1280 1368 1504 1728 1024 1025 1028 1069 -HSync +Vsync

   Option "PreferredMode" "1280x1024_75.00"

The ModeLine line may be obtained by looking at your current Xorg.0.log if the mode is already detected (when it appears in the output of xrandr). Or you may generate a new one using:

  $ gtf 1280 1024 75

  Modeline "1280x1024_75.00" 138.54 1280 1368 1504 1728 1024 1025 1028 1069 -HSync +Vsync

III.6. Example of modern configuration

Here's an example of xorg.conf for a ATI board with DVI-0 (with DisplaySize and preferred mode forced), LVDS (placed on the right of DVI-0) and VGA-0 (disabled) outputs.

Section "InputDevice"

   Identifier "Generic Keyboard"

   Driver "keyboard"

   Option "CoreKeyboard"

   Option "XkbRules" "xorg"

   Option "XkbModel" "pc101"

   Option "XkbLayout" "us"

EndSection

Section "InputDevice"

   Identifier "Configured Mouse"

   Driver "mouse"

   Option "CorePointer"

   Option "Device" "/dev/input/mice"

   Option "Protocol" "ImPS/2"

   Option "Emulate3Buttons" "true"

   Option "ZAxisMapping" "4 5"

EndSection

# external DVI with DisplaySize and preferred mode overriden

Section "Monitor"

   Identifier "External DVI"

   DisplaySize 304 228

   Modeline "1280x1024_60.00" 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync

   Option "PreferredMode" "1280x1024_60.00"

EndSection

# internal laptop panel to place on the right of DVI-0

Section "Monitor"

   Identifier "Integrated LCD"

   Option "RightOf" "External DVI"

EndSection

# disable VGA by default

Section "Monitor"

   Identifier "VGA-0"

   Option "Ignore" "true"

EndSection

Section "Device"

   Identifier "ATI Technologies, Inc. M22 [Radeon Mobility M300]"

   Driver "ati"

   BusID "PCI:1:0:0"

   Option "AccelMethod" "EXA"

   Option "Monitor-DVI-0" "External DVI"

   Option "Monitor-LVDS" "Integrated LCD"

   # no need to specific Monitor-VGA-0, it uses the "VGA-0" identifier automatically

EndSection

Section "Screen"

   Identifier "Default Screen"

   Device "ATI Technologies, Inc. M22 [Radeon Mobility M300]"

   DefaultDepth 24

   SubSection "Display"

   Depth 24

   # big virtual screen to place

   Virtual 3072 1200

   EndSubSection

EndSection

Section "ServerLayout"

   Identifier "Default Layout"

   Screen "Default Screen"

   InputDevice "Generic Keyboard"

   InputDevice "Configured Mouse"

EndSection